Colorado State University

Research - Current and Recent Field and Laboratory Research

The Center for Aerosol Impacts on Chemistry of the Environment (CAICE) (NSF-Chem)

(CAICE), based from the University of California - San Diego and Scripps Institution, is a Center for Chemical Innovation that is presently focused on understanding the chemistry and climate impacts of sea spray aerosols. Particles are produced by wave-breaking in a large laboratory wave channel and scaled systems for realistically reproducing particles from bubble bursting of seawater. Dr. DeMott is a Senior Personnel member of CAICE and co-lead of the Research Theme 3 regarding aerosol-climate impacts, Dr. Hill is a Research Scientist member, Russell Perkins is a postdoctoral scientist, and Kathryn Moore is a graduate student with the center.

(SOCRATES) occurred during January and February 2018, as part of a major Southern Ocean (SO) studies period that also included DOE-related studies (see below). Participants from several U.S. universities (funded by NSF), CSIRO, the Australian Bureau of Meteorology, and NCAR based from Hobart, Tasmania for in situ measurement and radar/lidar studies to investigate and help resolve global climate model radiation biases over the SO as having bases from aerosol/cloud microphysical versus dynamical sources. During SOCRATES, our group led comprehensive measurements of ice nucleating particles using equivalent suites of our CFDC instrument and Ice Spectrometer (IS) filter collections on the NSF/NCAR G-V aircraft and on the CSIRO R/V Investigator (CAPRICORN-2018 study – see photo of Ezra Levin and Kathryn Moore during installations). We also provided our WIBS-4A instrument for bioaerosol measurements on both platforms, and will conduct next-gen sequencing analyses of collected aerosols to assist understanding of cloud response to ocean biogenic aerosol emissions.

These two projects are funded and supported by the DOE Atmospheric Radiation Measurement Program’s Climate Research Facility, and analyses are now supported by a 2018 Atmospheric Systems Research Grant. Closely aligned with the multi-agency SOCRATES campaign, one objective of the Measurements of Aerosols, Radiation, and Clouds over the Southern Ocean (MARCUS) campaign (Greg McFarquhar, Oklahoma U., PI) is to help in understanding the sources, sinks, and variability of CCN and INPs, the increased bias of absorbed shortwave radiation in summer in models, and conditions conducive to occurrence of extensive supercooled water in the SO region. INP filter collections for offline processing using our IS instrument were deployed alongside the second ARM Mobile Facility's (AMF2) on the Australian Antarctic Division’s Aurora Australis during four Antarctic and Macquarie Island station resupply cruises between October 2017 and March 2018. Whereas MARCUS will provide spatial data over Spring through Fall seasons, the Macquarie Island Cloud and Radiation Experiment (MICRE) (Roj Marchand, U. Washington, PI) will provide seasonal and annual cycles of INPs, aerosol, and cloud properties at a single site (Macquarie station is at 54.6 degrees south latitude and 158.9 degrees east longitude). IS processing is underway to determine the temperature spectrum of the concentrations of INPs active via the immersion freezing mechanism across the temperature regime from 0 to -27°C. Additional analyses (thermal, chemical) will be used to discern the biogenic versus inorganic contributions to INP populations. Aerosol ionic, total carbon and genetic analyses of biological community diversity will also be performed and archived.

The Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption and Nitrogen (WE-CAN) study aims to better understand the chemistry of wildfire smoke. The project is funded by the U.S. National Science Foundation (NSF), supported by the National Center for Atmospheric Research (NCAR), and is led by Principal Investigators from Colorado State University, the University of Washington, the University of Colorado at Boulder, the University of Montana, and the University of Wyoming. Agency collaborators include NOAA and NASA, as this project precedes the FIREX and FIRECHEM studies in 2019. A flyer on the full project is here (Flyer). One of the largest instrument packages ever assembled on the NSF/NCAR C-130 aircraft will base from Boise, Idaho from 22 July - 31 August 2018. Our group is specifically addressing how wildfire smoke plume particles of different age affect the behavior and formation of liquid and ice clouds. Elevated wildfire plumes have not previously been sampled in a coordinated manner to evaluate for INP emissions and their evolution. We will be collecting INP measurements (number concentrations and compositions) via our online and offline instrumentation, CCN spectra, aerosol size distribution, and refractory black carbon measurements (SP-2). Sampling will occur from ambient air and a counterflow virtual impactor inlet for sampling smoke that has been ingested in clouds.

This project co-lead by Paul DeMott and Sonia Kreidenweis is a collaboration with lead PI, Paul Ziemann of the University of Colorado, and Markus Petters of N.C. State. Funding is provided by DOE grant DE-SC0018265. This study has primary objectives to 1) measure the effects of molecular structure, temperature, and relative humidity on the viscosity of SOA formed via controlled laboratory experiments; 2) assess the critical viscosity where semisolid SOA surfaces lose their heterogeneous ice nucleation properties; and 3) develop computationally inexpensive expressions to demarcate regions where aerosols are liquid, semisolid, glassy, and/or ice nucleation active. Experimental studies in our laboratory will involve characterization of the ice nucleation rates and surface active site densities of viscous/glassy citric acid and sucrose particles for comparison to the literature, using our newly refurbished long-column laboratory CFDC (with particle phase discriminator) operating between -40 to -60C. The CFDC will then travel to CU in the second year for studies of laboratory-formed SOA particles. These studies will produce new data on the deposition and immersion freezing ice nucleation of SOA at cirrus temperatures for use in regional and global atmospheric models, will identify if a critical equilibrium viscosity exists below which heterogeneous ice nucleation is not possible, and will identify the potential role of molecular structure on ice nucleation.

This study, funded by NSF grant AGS-1358495, has primary objectives to elucidate the nature of particles produced from various types of INP-emitting soils/Ecoregions, to better constrain the level of emissions and presence of ice nucleating bacteria, fungi and other biological INP to the atmosphere, and to understand the contributions of organic and inorganic ice nucleating particles emitted from plants and soils in general. Existing and new techniques are being applied for identifying biological/organic INP including advanced DNA analyses, and use of online aerosol mass spectrometric methods. The product of this research will be quantitative descriptions for use in numerically modeling the atmospheric distribution of INP sources from land, and their impacts on clouds in a changing climate.

CalWater1, CalWater2, ACAPEX (DOE ARM and ADSR)

CalWater is a multi-year study, including ground, ship, and aircraft campaign intensives, with a focus on two key phenomena that play key roles in the variability of the water supply and the incidence of extreme precipitation events along the West Coast of the United States: Atmospheric Rivers (ARs) that deliver much of the water vapor associated with major storms along the U.S. West Coast, and the modulating effects of aerosols (local, pollution, marine, and long range transported dust and biological particles) on western U.S. precipitation. The project has been supported at various stages by the California Energy Commission, the National Oceanic and Atmospheric Administration, the Department of Energy, the National Science Foundation, and the National Aeronautics and Space Administration. Our group's first participation in 2011 was to use ouf continuous flow diffusion chamber (CFDC) to measure ice nucleating particles from ambient (outside of clouds) and counterflow virtual impactor (within clouds) inlets onboard the DOE-ARM Aerial Facilities G-1 aircraft, based from McClellan Airfield in Sacramento, CA . Focus cloud systems were orographic clouds over the Sierra Nevada mountain range east of Sacramento, and cloud systems over the ocean and Coastal Range of California during February and March 2011. Ground-based observations in collaboration with the Prather Group at the University of California - San Diego followed in 2014 at the Bodega Bay Marine Laboratory. CalWater2 and the DOE-funded ACAPEX programs followed as a major field study in January through March 2015. CSU's effort included CFDC instruments on the G-1 and at Bodega Bay, filter sampling for INP post-processing with the Ice Spectrometer on the G-1, at Bodega Bay, and on the NOAA RV Ronald H. Brown ship. The CSU mobile laboratory (ADD) also operated at Bodega Bay in collaboration with the Prather group and the Petters Group from North Carolina State University to collect a large suite of measurements on aerosol physical, chemical, and cloud activation properties. Quicklook data are available via the "Atmospheric River Portal" operated by our colleagues at the Center for Western Weather and Water Extremes.

Ice in Clouds Experiment - Tropical (ICE-T) (NSF AGS-1036028)

We measured IN concentrations using the aircraft version of the CFDC
over the Carribean Sea in the vicinity of St. Croix in July 2011 on the
NSF/NCAR C-130 Hercules research aircraft. The campaign was interested
in ice processes in tropical cumulus clouds, which are poorly
constrained and understood. This campaign followed from the ICE-L campaign that
previously focused on ice initiation in stable orographic wave clouds
(Eidhammer et al. 2010;
Field et al. 2012
Field et al. 2012). We measured ambient IN concentrations in the
marine boundary layer, flying as low as 100 feet over the sea at times,
and also measured IN in cloud residuals by sampling from a counterflow
virtual impactor. A large range of trace gas, aerosol and cloud physics
measurements were performed on the C-130 as well as the SPEC Inc.
Learjet, which also participated. More information about the ICE-T
project is available here.

Studies of Ice Nuclei from Biomass Burning (NOAA NA10OAR4310103)

We are conducting a variety of measurements of biomass combustion, in
prescribed burns and Western wildfires. These studies augment previous research
in the laboratory.
Our goal is to quantify and identify IN emissions from fires, which may
have larger impacts on climate and precipitation. A first publication of
research results is here.
In Spring 2011, we took the CFDC instrument to Georgia to measure IN
emissions from prescribed fires at the Jones Ecological Research Center.
The fires are used to help maintain the lodgepole pine ecosystem that
once spread along the entire SE US continental plain. Fires were a
natural part of the ecosystem, but supression now means they rarely occur
naturally. Policy makers in the southeast have to balance the needs to
maintain both healthy forests and air quality. Recently, massive
wildfires in Colorado have reached to within 2 miles of our laboratory
and we have been sampling the smokes that occasionally blanket Fort Collins.

We are just beginning studies to obtain data to clarify the role of BC in ice
formation, and in aerosol-cold cloud interaction studies using satellite observations.
We will use a combination of controlled laboratory biomass combustion studies of plant
species from regions of global importance and atmospheric measurements from fixed sites to
measure the proportional contributions of BC versus other aerosol types toward atmospheric
IN populations and examine the dependence on sources and physical/chemical properties. The
primary laboratory campaign will be coordinated within the FLAME-4 study in October to
November 2012 in Missoula, MT. That study with collaborators from the University of
Montana, Carnegie Mellon University and others, and will include smog chamber studies of
smoke processing impacts. Key in our approach is to utilize novel combinations of existing
instruments (SP-2, HTDMA, CFDC) to measure the concentrations of freezing nuclei before and
after selective removal of BC particles, and to define the association of IN with particle
hygroscopicity, composition, BC content, and atmospheric processing (CMU smog chambers).
These measurements will provide the basis for revising (existing) and developing new numerical
descriptions of BC and other biomass burning aerosol activation properties as ice nuclei for use in numerical
simulations to predict the cold-cloud impacts of biomass burning emissions and ambient BC.
Parameterizations will be sought that can use remotely sensed data from present and future
satellite missions, such as global fire activity, aerosol optical depth, retrieved aerosol
microphysical and optical properties, and carbon monoxide, to observationally constrain IN
number concentrations.

BEACHON-RomBAS (NSF) Studies of Cloud Active Aerosols Over Forests

The BEACHON-RomBAS (Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics & Nitrogen
- Rocky Mountain Biogenic Aerosol Study) field intensive was a multi-investigator study
conducted at the Manitou Forest Experiment Station near Woodland Park, CO, during July and August 2011
(website). The study helped fulfill multiple objectives,
all of which are aimed at the goal of assessing the influence of ecosystem processes, and their responses
to climate, on the number and composition of climatically-relevant biogenic aerosols and their potential to function as CCN
and IN, and to modify precipitation. Our activities under NSF ATM-0919042 focused on collecting annual
cycle data on CCN activity/hygroscopicity of biogenic particles (Levin et al. 2012)
and speciation of primary biological particles, and on measuring IN activity and its association with primary
biological particles and other environmental influences during the field study intensive. IN measurements included
application of pre-concentration of aerosols and collection of IN for both biological and chemical speciation,
all for the first time. Multiple publications are in preparation.